Method of and apparatus for electrolyzing liquid



- `Mambov oF. AND 'APP/rmi@ FDE ELEcTRoLYzNG Lxdul D.A

.F11-wma 1&,1915

` Patented Janf; p

y p NHT 11" AHintii--i1ri-i' H. Dow, ,'rHoiviAs qRiswoLD, JR., A NDDDwIN o`.,.BARsTow, or 1ir1D1-,AND,A

MICHIGAN, AssIGNoRs To THE DoWcHEMIcALj COMPANY, or MIDLAND, -MICHI- GANQA CORPORATION 0F MXCHIGAN.

ivin'riionor AND APrARA'rUs ron ELEcTNoLYziNG LIQUID.

Application file-i August 1.2, 19'1`5. i serial N. 45,096.

To all whom t may concern g Y Be it known that we, HERBERTH, Dow,l ='I`I ro.i\iAs GRisWoLD, J r., andv EDWIN O. BAR- s'row, all citizens of the United States, residing at Midland, the county of Midlandand State of Michigan, have invented a cerf tain new and useful Improvement in Methods ofl and Apparatus for Electrolyzing Liquid, 'v ,of which the following is a full, clear,v and' exact' description, referencev being had tothey accompanying drawings.

This invention 'rela-testo the art` of electrolyzing liquids and has particular connec,

i -tion with the electrolysis of alkali halide for l. l u u n thoughnot limited tofsuch use.- The ob]ects the production of halide and causticyal-v ofthe invention are the provision 'of aV I method and apparatus whereby power-.lossis 'l 'minimized and. whereby the Ypu'rity'of the elluent is increased; theprovisionof means -ploy1 has been noted that the frictional resistance to thef flow causes thelirquid level'in -each cell I -normallyi'to stand a slight distance below that in' the precedingcell so that in case a large number of cells is employed the difference in, height of this liquid surface from rst tollast becomes rather an appreciable amount. Mechanical considerations, however, render alevel arrangement o f cells desirable, added *do which isthe factl that it is sometimes desired to maintain a iiow of anolyte as well as of catholyte. In addition,.in vpractical use, it i'ss'om'etimes desirable to ein- ,cellsof the'bpolar electrode type, in which the electrodeplatesthemselves form thewalls between adjacent cells, and this arrangement renders diiiicult or awkward any arrangement of cells other than-en 'a level.

According to ourinvention we arrange the various cells substantially level, and' makeforpropelling electrolyte from cell to cell of vfuse ofh the gases .evolved by th'e electrolysis a seriesof cells placed upon' the same level while rnaintaining the saine liquid level in adjacent cells; the diminution of short cir-fy cuiti'ng and current loss; `while further'ob jects and advantages. will hereafter appear.

Itvhas hereto'forebeen proposedto' con-l'v duct the electrol is of alkali halide in apluf rality of cells o the diaphragm type, transthey flow resistance otherwise'observed. r1 his arrangement offers 'the' further.. advantage Y that the gas bubbles in the pipes 'increase'the electrical resistanceftherein toisuch an eX- tent'v as greatlyfto decreasethe shunting of 30 ferring the catholyte successively from*v cell the current' fromv cellto cell and thus cut 80 to cell so as tofobtain an increnient'of cansticity -in Aeach cell, while A'dimini'sl'iing the averageA difference in liquid composition upon the opposite side of the diaphragm in "35 5 4the various cells, thus decreasing the tendency. todiffusion and with it the power'lo'ss.

i I It iswell settled that 'diffusion of the cathode K liquid not only causes a'loss of 'power bi'i't. 'al-socontaminates the product and seriously injures the anode plates of thecells.- For l the most efficient operation the* liquid pres` sure in the anode chambers .of the various. cells is therefore maintained-abovethat in ,the cathodechanibers, 4thu'stending to set up oit' arvinafterial waste of power- -An addil tional advantage -of this arrangement resides .in the'fact that the velocity ofthe liquid vflow is caused -to Vdepend with` veiy substantial accuracyupon the rapidity ,of electrolysis,

so thatthe amount of decomposition in eachl cellis automatically gaugedgand, further,

the flow of electrolyte ceases immediately rent, so thatv the cells are always lled with' electrolyte and are ready for operation with- 'out dan er of becoming accidentallydrained or over lled.

uponthe interruption of the elect-ric cur- I -Inthe drawings accompanyingand forming apart of this application We have illustrated certain apparatus-whereby. the proc" esses and objects of this invention'may be realized, although it will be understood that these drawings `are merely. diagrammatic, and that they are not intended to be eXhaus2 15 W bers by means of a. and with the `anodes cated upon opposite sides thereof and connected and arranged in accordance with oui-- tive ot all the arrangements, connections, or systems' whereby the principle et our invcntion may be utilized. ln these drawings: Fig. l represents afvertical, diagrammatic, sectional view through a series of cells coninvention5' and'Fig. 2 represents in idealized form an arrangement of our invention adapted for use with cells of the bipolar type..

First describing Fig. l, El, E?, E3- and E? represent the variouscells, four of the same being shownhere, although it will -be un#` derstood that the arrangement shown could be extended to any length" desired. Each of these cells is separatedinto two champorous 'diaphragm D nected electrically `in any suitable'manner. The upper portions of the cells are preferably chambered upon oppositesides of the diaphragm as shown lat F and G, these cham bers being separated-.by an impervious sep'- tum H. Leading upwardly from the chambers F are the discharge pipes w1,a2, as and n-respectively, and communicating at their uppe'rends with a manifold P.- Projecting laterallyfrom these pipes are the conduits b1., b, b3 and be?, respectively, all excepting the last of which discharges -into the anode chamber of the succeeding cell.

LeadingH upwardly; the` chambers G are the-discharge. pipes c1., c?, cf" and' c4 conf nected at their upper ends vto a manifold' Q,"

and to the sidesof. these pipes 'are connected the conduits djdd and d4, respectively,

alll excepting the last of which `comm''unicatewith the" cathode-chamberfof the adjacent Acel-l. 4 'Il he last of these cond.uitsd4forms the ultimateeiiuent discharge.

It will be noted that the polntfof 'comico-. tion between 'the pipes ai and b is higherthan thatA ofthe pipes@ and d in every case, this bei-ng .,or the'- purpose. of. maintaining. a

higher. head of electrolyte t lre"anode .I chamber 'than 1in the cathode chamber.

With the arrangement .shownin .this View the, operation islas follows: Supposing that sodium chloride isto be electrolyzed forfthe productionfof {chlorin and caustifc" so'd`a.. A?

"solutionofsod'iu'm chlorid being' introduced into' all offthe cells, the',v fpplicationof an electric current inl such as to `render -the plates A anodes' and.. plate'sfc'athodes,

will cause a depletionef thesodium-chlo'rid` cont'ent inthe anode chambers with,. an. evo? lution' o f 4chlorin gasp 'and a Tsinrultane'ous production .of caustic soda in-the cathode chambers with the evolution, of hydrogen gas. The cells are normally fil'ledwith solui tion as high. aspossible, .in this case't'o the f point defined bythe intersection 4'o theV and cathodes C lo#v The conduit b4 of the last cell is shown as communi-- eating'v withthe cathode chamber of 'the same i eee the hydrogen collecting' in the chambers G- rises in bubbles in ythe pipes c1, c2, c3, @A elevating the cathol'yte. therein so as .to propel it into' the tubes (Z1, d2, (Z3, d4, respectively, whence it tlows'to the cathode chamber ofthe .adjacent cell. In-the case ofthe last cell theliquid from the pipe-attlows' to the cathode compartment of thesame cell, but without danger of short circuitingthe .cell through the liquid because ot the tact that the bubbles in the pipe at are not conductors and'also ordinarily because of the fact that there is a'very noticeable difference l i in level betweenthe catholyte and anolyte. The liquid ejected through the 4 last conduit cf* is thatVrichest/in caustic vand is ultimately treated for recovery of this material in any suitable orf desired manner. Rawbrine to replace that 'withdrawn -is 4added atthefinlet" (L. The chlorin gas evolved isreeovered from themanifold P and hydrogen gas-'from the manifold Q, while the purpose ofthe septa H`H is to keepfthe gases-apart, rendering them vbetter suited for use ajnd pre-` venting` the danger of an explosion..

' In Fig.2 we have shown the edaptation of' our improvement toelectrolytic cells of the bipolar electrode type, in which 4 the cell bodies H-H consists otopenendedz boxes or' casings traversed -interiorly .by plates I I of conducting material tightly' .secured therein, Vsaid casings beingsecuredltogether.

diaphragms D -D` int.e i'posed between their adjacent ends. "The terminal cells-.shown 'at JwJ-.are -similartothe cells excepting th'atweachf comprises' only a-'"single chamber and contains a single conducting plate .arranged to serve-as' an electrode.l The up- '1* per p arts of these cells are'preferably formed `as beforewithl chambersEF andGr spaced `from the. forwarilacesof,` the bodies, which form enect' the -septa In' the presanode andl tlie. ..si mi lar plate at the left hand endtfhe nalyfcathode, theopposite s ideslof ``the "intermediate platesfserving anode and- Cathodetunctions inthey usualmanner.

.Communicating wlth the chambers F are v --'..w-hilef communicating with the chambers. G

are' the uprightv pipes b4, c1, 02 03,'04', all, (Z2

andfdS-g The pipes al, t2,"etc., communicate 'with thexmanifold P, and the pipes 0 1, c2,l etc., with themanifoljd operation :face -to face in any convenient mannerwith out further elucidation.

' It will be understood thatthe above .are

vi'nten'ded't'o be only diagrammatic views, and thatthe foregoing description is intended tof halide solution for caustic alkali and free set forth onlya f ew ofthe great numbers of embodiments'to. which our invention "is sus- Y ceptible'and to point out only a part of the apparatus by means of. which our improved process may" be .utilizedv In both` of the foregoingstructures it will be observed that the pipes (11,02, etc., have-a diameter which bears such proportion to their vlength as .that the evolved gases during'jthe ascent .therethrough convey the electrolyte. First of all, the upper lporwith them portions of tion of the cell is divided by the septa H intoI separate chambers wherein the 'gases from the anode and cathode compartments, respectively, may collect,- and then itis from these chambers that the pipes or 'ductsof either reduced diameter or crosssectional area rise.

For example, inthe electrolysis-cfa halide yalkali for halogen and caustic the advantages gained byY propulsion of the catholyte from cell to cell far"o'utweighfthe 'advantages gan'ed byjsimilar 'propulsion of the anolyte. So far as the electrical and electro'chemicalfeatures of thep-rocessare con-` cerned, the anodecompartme'nts might be' fedin parallel and .only the lcathode compartments loperated in Series; and, cony versely, inthe electrolytic production 5'of other substances it might'be 'more-desirable Vto treat theanolyte in successive cells without moving the catholyte.

In the present applicationV we haveillustrat'ed the movement of both liquids, "partly to show how it Amay-be accomplished.. and *f partly :from the' fact that the automatic propulsion f the anolyte exhibits certain advantages of regulation,- suchas'maintaining the anolyte ever, in the case of a long series of cells it A claims. j

in all the cells at aunif'orm level during the How of currentand'instantly stopping the.

flow upon interruption of the current. Howmaybe desirable 'to add fresh liquor at in# tervals ,to prevent impoverlshment and consequentincrea'se of reslstance.' Such vari- .ationsare not modifications but rather different aspects of our same invention', and lall such variations. and 'modlfications are intended to be included jin the following Having'thusdescribed our invention, we claim-:-

1. In theprocess of producmg caustic alkaliwh-ichf consists .in `passlng an aqueous solution of a Ihalide salt of said alkali successively through the cathode'ch'ambers of 'a plurality of electrolytic cells ofthe diaphragm type, the stepwhich consists' in `uti+ lizing the buoyancy of the gases lberated' in 4each cathode chamber to elevate the cathvolyte treated thereinto a higher level than that of the catholyte inv the succeeding cathode chamber.

2. In a method of electrolyzing an alkali- A .chloride solution for chlorine and caustic whi-ch the electrolyte is treated successively in a seriesof electrolytic cells, whereby an increment of causticity is produced in each cell, the step ,which consists in utilizing the buoyancy of the liberated gases to expel the electrolyte from each cell at a rate subs tantially proportional to the rate of caustic production therein. i

4. In a method of 'electrolysis in which the electrolyte is treated'successively in aplu- 90 rality of cells with the production 0f a solute and anevolved gas', the step which consists in utilizing the buoyancy of said gas tov expel the electrolyte from that cellat a rate substantially proportional tothe rate of productionofsolute, .`whereby the concentration ofthe solute is limited. l

'5I rI`he process of producing caustic alkali which consists in electrolyzing a solution of a halide saltof(` said alkali in a'series of '10s closed cells of the diaphragm type, discharging the evolved gases through upwardly extending `conduits communicating with the upper-part o f each cell, whereby a certain portion of the electrolyte is expelled continuously frolneach `ce ll,conveying such ex- -pelled electrolyte to the next cell, 'and supplying new solution totake. its place.

6. In amethod of. electrolysis in -which an electrolyte'is treated successively in a' plu- 10 rality ofelectrolytic cells, the liquid treated in each cellbeing passed toothereells for` further treatment, the -step which consists in discharging the evolved gases through *the same conduits as'the liquid, whereby anA 115 active movement of the liq1 '1id fis -produced and the passage of electric "urrent'- along the liquid isretarded.

7. In a method of electrolysisin which the electrolyte is treatedsuccessively in a plurality of electrolytic cells with the. produc.'- tion of a solute and an evolved gas,the

-steps whichlconsist -in discharging such gasi ceeding cell.

S. The process of electrolyz-ing an alkalihalide solution for halide and caustic alkali 'which consists in adding to the anode chambei' o t' a diaphragm cell a greater quantityofsolution than said diaphragm can transmit by percolation, discharging theevolved cathode chambers of succeeding cells until4 Nthe desired causticity is attained.

9. Apparatus for electrolyzing liquids to produce a solute and an' evolved gas comprising the combination, with anv electrolytic cell,` of means' for collecting vthe gases` evolved therein,` a restricted passage com munic'ating with the electrolyte therein, meansfor discharging such gase'svthrough said passage so as to induce a flow of electrolyte therethrough, and means `for conveying said electrolyte to another cell.

1-0. Apparatus for electrolyzing liquids to produce a. solute and an evolved gas, comprising in combination, a plurality of electrolytic cells arranged substantially upon a level, thetop of each of said cells being closed to provide a collectingA chamber, a. re-

stricted conduit communicating with each chamber, and a side branch communicating` withsaid conduit above the top of each cell land leading to the next cell, said branch `communicating with the 'succeeding cellat a point below the level of the conduit therein.v

11.V In apparatus for electrolyzing liquids to produce a'solute and an evolved gas, the combination with an electrolytic' cell of the diaphragm type, the top of said .cell being closed to providev independent collecting compartments uponv opposite sides .of the diaphragm therein, of a restricted conduit leading upwardly Vfrom each of said com partments, aside branch communicating with each of said conduits at a point above said cell, the point of connection between the conduit leading from the anode chamber and' its side branch being higher than the point of connectionl between Athe conduit leading from the` cathode chamber and its side branch, andmeans for feeding'electrolyte to eachiof said chambers.

12. Apparatus for electrolyzingliquids to produce al solute and an evolvedgas, comprising, in combination, a plurality of electrolytic cells of the diaphragm type, the top of each cell being closed to provide independent gas collectingcompartments upon ,opposite sides of the diaphragm therein, arestrict-ed conduit 1leading upwardly'. from each of said compartments, -a side branch communic-ating with each of said conduits at a point above said cell, the branch from each anode conduit communicating with the anode chamber of the succeeding cell and the branch from each cathode conduit communica'tingwith the cathode chamber ot the preceding cell, and meansjfor feeding ele"- trolyte vcontinuously to the first anode '-13'. Apparatus for electrolyzing liquids .to 'produ-ce a solute andan evolved gas, comprising, in combinatiolna plurality of electrolytic cells ,of the .diaphragm type, the top of each cell being closed to provide independent gas collecting'V compartments upon opposite sideS'o' the diaphragm therein, a restricted conduit leading upwardly from each of said lc-'omp'artments, 'a sidebranchcommunicating with each-l of said conduits at a point above ,sai-idcell, the branches from the anode conduits discharging at a higher level lthan the branches from the cathode conduits,

each of thecathode branches communicating with the cathode chamber of the succeeding`- cell, and'means for delivering electrolyte to 'i each` anode chamber.

14. Apparatus forA electrolyzing liquidsto produce a solutev and an evolved gas, coml prising,' in combination, a. plurality of electrolyticcells ofthe diaphragm type, the top of each cell being closed to provide independv ent gas collecting compartments'upon opposite sidesof the diaphragm therein, a restricted conduit lea-ding upwardly-'from each i i of said compartments, aside branch communicatingwith each of said conduitsat a point abovesaid cell, the branches from the anode conduits being. arrangedat one llevel j and the branches from the cathode conduits i being also disposed upon a level but lower than 'said' anode branches, veach of said anode branches communicating with aqs'ucceeding anode' chamber andeachfofsaid cathode' branches communicating with 'a' succeeding cathode chamber.

halide solutions for the'production of caustic 15. Inapp'aratus for el'vectrolyzing alkali alkali and free halide, the combination, with a plurality 'of electrolytic cells, said cells havin'g' diaphragms vbetween the electrodes andthe topsofsaid cells being covered topro-vide independent gas-collecting compart ments on each side of the diaphragm, of a restricted conduit leading upwardly. from each compartment; and a side-branch communicatingwith each conduit -ata Apointl above the cell, the branches from the anode conduits being led to other anode chambers', and the branches` from the cathode conduits being led to othercathode chambers.

16. In an apparatus for 'electrolyzing liquid to 'produce a solute and an 'evolved gas, the combination with a plurality of electrolytic cells,"each of which is divided a porous diaphragm into'a pair of com'- lioy pertinents, said cells havngthe tops of our signatures in the presence'of two Witsimilar comprtments closed to form collectnesses.

ingv chambers, of a restricted lconduit lead- HERBRTlI-I, DOW. ing from each chamber, and means for con- THOMAS GRISWOLD, JR. veying any liquid propelled through said EDWIN O. BARSTOW.

conduit into the similar fcompzirtlnent; of a Witnesses:` succeeding cell. v JAME'sT. PARDEE,

In testimony whereof', We hereunto aix A. W. SMITH. 

